Silybin regulates P450s activity by attenuating endoplasmic reticulum stress in mouse nonalcoholic fatty liver disease.

Abstract

Cytochrome P450s are important phase I metabolic enzymes located on endoplasmic reticulum (ER) involved in the metabolism of endogenous and exogenous substances. Our previous study showed that a hepatoprotective agent silybin restored CYP3A expression in mouse nonalcoholic fatty liver disease (NAFLD). In this study we investigated how silybin regulated P450s activity during NAFLD. C57BL/6 mice were fed a high-fat-diet (HFD) for 8 weeks to induce NAFLD, and were administered silybin (50, 100 mg ·kg-1 ·d-1, i.g.) in the last 4 weeks. We showed that HFD intake induced hepatic steatosis and ER stress, leading to significant inhibition on the activity of five primary P450s including CYP1A2, CYP2B6, CYP2C19, CYP2D6, and CYP3A in liver microsomes. These changes were dose-dependently reversed by silybin administration. The beneficial effects of silybin were also observed in TG-stimulated HepG2 cells in vitro. To clarify the underlying mechanism, we examined the components involved in the P450 catalytic system, membrane phospholipids and ER membrane fluidity, and found that cytochrome b5 (cyt b5) was significantly downregulated during ER stress, and ER membrane fluidity was also reduced evidenced by DPH polarization and lower polyunsaturated phospholipids levels. The increased ratios of NADP+/NADPH and PC/PE implied Ca2+ release and disruption of cellular Ca2+ homeostasis resulted from mitochondria dysfunction and cytochrome c (cyt c) release. The interaction between cyt c and cyt b5 under ER stress was an important reason for P450s activity inhibition. The effect of silybin throughout the whole course suggested that it regulated P450s activity through its anti-ER stress effect in NAFLD. Our results suggest that ER stress may be crucial for the inhibition of P450s activity in mouse NAFLD and silybin regulates P450s activity by attenuating ER stress.

• Authors: Jing Wu, Yun-Ge Lou, Xu-le Yang, Rui Wang, Ran Zhang, Ji-Ye Aa, Guang-Ji Wang, Yuan Xie
• Journal: Acta pharmacologica Sinica (Acta Pharmacol Sin) Vol. 44 Issue 1 Pg. 133-144 (Jan 2023) ISSN: 1745-7254 [Electronic] United States
• PMID: 35705686 (Publication Type: Journal Article)
• Copyright: © 2022. The Author(s), under exclusive licence to Shanghai Institute of Materia Medica, Chinese Academy of Sciences and Chinese Pharmacological Society.

Chemical References

• Silybin
• Cytochrome P-450 CYP3A
• Cytochrome P-450 Enzyme System

Topics

• Mice
• Animals
• Non-alcoholic Fatty Liver Disease (drug therapy, metabolism)
• Silybin (pharmacology, metabolism)
• Cytochrome P-450 CYP3A (metabolism)
• Mice, Inbred C57BL
• Cytochrome P-450 Enzyme System (metabolism)
• Diet, High-Fat (adverse effects)
• Endoplasmic Reticulum Stress
• Liver (metabolism)